Silicon chips have billions of transistors in every square inch. But sometimes there’s enough room left over for chip engineers to insert a little joke.

While using a scanning electron microscope to examine the microcircuitry of a chip found in Samsung’s Galaxy Tab and Galaxy S phone, consulting company Chipworks discovered a surprise.

Underneath six layers of aluminum and silicon dioxide circuitry, almost at the level of the polysilicon wafer that underlies the entire chip, engineers concealed a tiny, tiny message.

Below the letters IFX (the stock symbol for Infineon, the company that makes the chip) is a tiny warning, made out of letters just two microns (2 µm) high:

IF YOU CAN READ THIS YOU ARE MUCH TOO CLOSE

“You would never find this message unless you were seriously looking for it,” says Chipworks marketing manager Rob Williamson.

The chip, the Infineon PMB5703, provides radio-frequency transmission and reception functions relating to the devices’ baseband and 3G features.

The tiny message is hidden in the upper right corner of the Infineon chip, in the square highlighted here. (Click the image to see a large photo of the full chip.) Image courtesy Chipworks

Chipworks has put many chips under the scanning electron microscope and has discovered dozens of hidden images and messages like this one. Constructed of the same materials as the chip’s circuitry — silicon dioxide, aluminum, copper and the like — the artwork can include cartoons, icons, or merely the initials of the chips’ designers.

In many cases, this artwork is not only tiny, it’s completely invisible unless you are disassembling the chip. Before it found this message, for instance, Chipworks had to delaminate the chip, layer by layer, putting each layer under the microscope. The purpose of that project was to understand the chip’s architecture, not to find hidden messages, but sometimes these Easter eggs pop out.

The makers of the Infineon PMB5703 must have had some extra time on their hands, because Chipworks found no less than four other images on the chip, including a smiley face, a drummer, a baby duck called Calimero and a smiling dragon named Grisu.